System information scheduling in machine type communication

ABSTRACT

The present disclosure relates to an apparatus for receiving system information in a wireless communication system including a receiver that receives system information configuration information and receives system information in predetermined subframes of a radio interface, and a controller that determines the predetermined subframes according to the received system information configuration information and controls the receiver to receive the system information in the predetermined subframes, wherein the system information configuration information includes a subframe scheduling field with a plurality of bits, each bit being associated with a subframe and representing whether or not system information is to be received in that subframe. The present disclosure further relates to a corresponding apparatus for transmitting system information and to the respective receiving and transmitting methods.

BACKGROUND Technical Field

The present disclosure relates to transmission and reception of systeminformation in a wireless communication system.

Description of the Related Art

Third-generation mobile systems (3G) based on WCDMA radio-accesstechnology are being deployed on a broad scale all around the world. Afirst step in enhancing or evolving this technology entails introducingHigh-Speed Downlink Packet Access (HSDPA) and an enhanced uplink, alsoreferred to as High Speed Uplink Packet Access (HSUPA), giving a radioaccess technology that is highly competitive.

In order to be prepared for further increasing user demands and to becompetitive against new radio access technologies, 3GPP introduced a newmobile communication system which is called Long Term Evolution (LTE).LTE is designed to meet the carrier needs for high speed data and mediatransport as well as high capacity voice support for the next decade.The ability to provide high bit rates is a key measure for LTE.

The work item (WI) specification on Long-Term Evolution (LTE) calledEvolved UMTS Terrestrial Radio Access (UTRA) and UMTS Terrestrial RadioAccess Network (UTRAN) is finalized as Release 8 (LTE Rel. 8). The LTEsystem represents efficient packet-based radio access and radio accessnetworks that provide full IP-based functionalities with low latency andlow cost. In LTE, scalable multiple transmission bandwidths arespecified such as 1.4, 3.0, 5.0, 10.0, 15.0, and 20.0 MHz, in order toachieve flexible system deployment using a given spectrum. In thedownlink, Orthogonal Frequency Division Multiplexing (OFDM) based radioaccess was adopted because of its inherent immunity to multipathinterference (MPI) due to a low symbol rate, the use of a cyclic prefix(CP) and its affinity to different transmission bandwidth arrangements.Single-carrier frequency division multiple access (SC-FDMA) based radioaccess was adopted in the uplink, since provisioning of wide areacoverage was prioritized over improvement in the peak data rateconsidering the restricted transmit power of the user equipment (UE).Many key packet radio access techniques are employed includingmultiple-input multiple-output (MIMO) channel transmission techniquesand a highly efficient control signaling structure is achieved in LTERel. 8/9.

The overall architecture is shown in FIG. 1 and a more detailedrepresentation of the E-UTRAN architecture is given in FIG. 2 . TheE-UTRAN consists of an eNodeB, providing the E-UTRA user plane(PDCP/RLC/MAC/PHY) and control plane (RRC) protocol terminations towardsthe user equipment (UE). The eNodeB (eNB) hosts the Physical (PHY),Medium Access Control (MAC), Radio Link Control (RLC) and Packet DataControl Protocol (PDCP) layers that include the functionality ofuser-plane header-compression and encryption. It also offers RadioResource Control (RRC) functionality corresponding to the control plane.It performs many functions including radio resource management,admission control, scheduling, enforcement of negotiated uplink Qualityof Service (QoS), cell information broadcast, ciphering/deciphering ofuser and control plane data, and compression/decompression ofdownlink/uplink user plane packet headers. The eNodeBs areinterconnected with each other by means of the X2 interface.

The eNodeBs are also connected by means of the 51 interface to the EPC(Evolved Packet Core), more specifically to the MME (Mobility ManagementEntity) by means of the S1-MME and to the Serving Gateway (SGW) by meansof the S1-U. The S1 interface supports a many-to-many relation betweenMMEs/Serving Gateways and eNodeBs. The SGW routes and forwards user datapackets, while also acting as the mobility anchor for the user planeduring inter-eNodeB handovers and as the anchor for mobility between LTEand other 3GPP technologies (terminating S4 interface and relaying thetraffic between 2G/3G systems and PDN GW). For idle state userequipments, the SGW terminates the downlink data path and triggerspaging when downlink data arrives for the user equipment. It manages andstores user equipment contexts, e.g., parameters of the IP bearerservice, network internal routing information. It also performsreplication of the user traffic in case of lawful interception.

The MME is the key control-node for the LTE access-network. It isresponsible for idle mode user equipment tracking and paging procedureincluding retransmissions. It is involved in the beareractivation/deactivation process and is also responsible for choosing theSGW for a user equipment at the initial attach and at time of intra-LTEhandover involving Core Network (CN) node relocation. It is responsiblefor authenticating the user (by interacting with the HSS). TheNon-Access Stratum (NAS) signaling terminates at the MME and it is alsoresponsible for generation and allocation of temporary identities touser equipments. It checks the authorization of the user equipment tocamp on the service provider's Public Land Mobile Network (PLMN) andenforces user equipment roaming restrictions. The MME is the terminationpoint in the network for ciphering/integrity protection for NASsignaling and handles the security key management. Lawful interceptionof signaling is also supported by the MME. The MME also provides thecontrol plane function for mobility between LTE and 2G/3G accessnetworks with the S3 interface terminating at the MME from the SGSN. TheMME also terminates the S6a interface towards the home HSS for roaminguser equipments.

The reception of system information (SI) is an operation to be performedby a UE on the basis of a scanned RF signal and a detectedsynchronization signal. In particular, upon the detection ofsynchronization signals the UE is capable of identifying a cell and ofsynchronizing with downlink transmissions by the cell. Accordingly, theUE may receive a broadcast channel, BCH, of a cell, and, hence, thecorresponding system information. On the basis thereof, the UE candetect whether or not a cell is suitable for selection and/orreselection, i.e., whether the cell is a candidate cell.

System information is information which is transmitted in a broadcastmanner to all UEs in a cell. It includes information necessary for cellselection and some parts thereof are to be read at any cellselection/reselection, after the UE synchronizes with the cell.

System information is structured by means of System Information Blocks(SIBs), each of which includes a set of parameters. In particular,system information is transmitted in a Master Information Block, MIB,and a number of System Information Blocks. The MIB includes a limitednumber of the most essential and most frequently transmitted parametersthat are needed to acquire other information from the cell such as thedownlink system bandwidth, an indicator of the resources allocated toHARQ acknowledgement signaling in the downlink, and the System FrameNumber (SFN). The remaining SIBs are numbered; there are SIBs 1 to 13defined in Release 8.

SIB1 contains parameters needed to determine if a cell is suitable forcell selection, as well as information about the time domain schedulingof the other SIBs. SIB2 includes common and shared channel information.SIBs 3 to 8 include parameters used to control intra-frequency,inter-frequency and inter-Radio Access Technology (RAT) cellreselection. SIB9 is used to signal the name of a Home eNodeB, whereasSIBs 10 to 12 include the Earthquake and Tsunami Warning Service (ETWS)notifications and Commercial Mobile Alert System (CMAS) warningmessages. Finally, SIB 13 includes MBMS related control information.

The system information is transmitted by the RRC protocol in three typesof messages: the MIB message, the SIB1 message and the SI message. TheMIB messages are carried on the Physical Broadcast Channel (PBCH)whereas the remaining SIB1 and SI messages are at the physical layermultiplexed with unicast data transmitted on the Physical DownlinkShared Channel (PDSCH).

The MIB is transmitted at a fixed cycles. The SIB1 is also transmittedat the fixed cycles. In order to improve robustness of the systeminformation transmission, the system information is repeated. Therepetitions have different redundancy versions and thus, they are notrepetitions of the bits effectively transmitted but rather repetitionsof the data carried but coded differently. For instance, MIB istransmitted every frame in the first subframe (subframe #0) wherein thenew MIB (MIB with content possibly different from the previous MIBs) istransmitted every four frames and the remaining three frames carry itsrepetition. Similarly, repetition coding is applied for transmission ofSIB 1. A new SIB1 is transmitted every 8 frames. Each SIB1 has threefurther repetitions.

All other SIBs are being transmitted at the cycles specified by SIBscheduling information elements in SIB1. In particular, the mapping ofSIBs to a SI message is flexibly configurable by schedulingInfoListincluded in SIB1, with restrictions that each SIB is contained only in asingle SI message, and at most once in that message. Only SIBs havingthe same scheduling requirement (periodicity) can be mapped to the sameSI message; SIB2 is always mapped to the SI message that corresponds tothe first entry in the list of SI messages in the schedulingInfoList.There may be multiple SI messages transmitted with the same periodicity.

Thus, a terminal determines the SI-window based on the signaledinformation and starts receiving (blind decoding) of the downlink sharedchannel using the SI-RNTI (an identifier meaning that signalinginformation is transmitted) from the start of the SI-window and continuefor each subframe until the end of the SI-window or until the SI messagewas received, excluding the subframe #5 in radio frames for which SFNmod 2=0, any MBSFN subframes, and any uplink subframes in TDD. If the SImessage was not received by the end of the SI-window, the reception isrepeated at the next SI-window occasion for the concerned SI message.

In other words, during blind decoding, the UE tries to decode PDCCH oneach subframe of an SI-window by using the SI-RNTI but only some ofthese subframes really carry PDCCH (CRC) encoded using the SI-RNTI(corresponding to PDSCH containing the particular SI).

For further details on the definition of system information, see forexample 3GPP, TS 36.331, V12.5.0, “3rd Generation Partnership Project;Technical Specification Group Radio Access Network; Evolved UniversalTerrestrial Radio Access (E-UTRA); Radio Resource Control (RRC);Protocol specification (Release 12)”, sections 6.2.2.7 and 6.3.1,available at http://www.3gpp.org and incorporated herein by reference.

As LTE deployments evolve, operators strive to reduce the cost ofoverall network maintenance by minimizing the number of RATs. In thisrespect, Machine-Type Communications (MTC) devices is a market that islikely to continue expanding in the future.

Many MTC devices are targeting low-end (low cost, low data rate)applications that can be handled adequately by GSM/GPRS. Owing to thelow cost of these devices and good coverage of GSM/GPRS, there is verylittle motivation for MTC device suppliers to use modules supporting theLTE radio interface.

As more and more MTC devices are deployed in the field, this naturallyincreases the reliance on GSM/GPRS networks. This will cost operatorsnot only in terms of maintaining multiple RATs, but also preventoperators reaping the maximum benefit out of their spectrum (given thenon-optimal spectrum efficiency of GSM/GPRS). With users and trafficbecoming denser, using more spectral-efficient technologies, such asLong Term Evolution (LTE), allow the operators to utilize their spectrumin a much more efficient way.

Given the likely high number of MTC devices, the overall resource theywill need for service provision may be correspondingly significant, andinefficiently assigned (for further details on objectives for MTC, seefor example 3GPP, RP-150492 Ericsson: “Revised WI: Further LTE PhysicalLayer Enhancements for MTC”, section 4, available at http://www.3gpp.organd incorporated herein by reference).

Approaches to lower the cost of LTE presently regard the volume ofproducts as the primary reason. The impact of volume can be seen in twopossible ways, depending on how low-cost MTC is developed. Firstly, iflow-cost MTC may be very similar to mainline LTE and included in LTEchipsets, MTC has the benefit of the volume of LTE. Secondly, a low-costMTC based on LTE may have significantly lower cost than mainline LTE.Although it appears not to have the volume benefit of LTE, the volume ofMTC devices can be even larger due to a potentially greater number ofsupported MTC applications and scenarios.

In this respect, the following approaches to lower the cost of LTE,i.e., defining low-cost MTC are discussed and found to have significantUE cost impact (for further details on low-cost MTC devices, see forexample 3GPP, R1-112912, Huawei, HiSilicon, CMCC: “Overview on low-costMTC UEs based on LTE”, section 4, available at http://www.3gpp.org andincorporated herein by reference):

-   -   Reduction in supported bandwidth for the low-cost LTE: The low        cost of 1.4 MHz (6 RB) downlink bandwidth could cover most        application scenarios of MTC. However, 3 MHz (15 RB) or 5 MHz        (25 RB) could be considered given that the complexity does not        increase much. Given that the uplink may have a larger        requirement for MTC services, the possibility of reduced        transmit power, and small baseband complexity (relative to        downlink reception), any reduction in minimum transmission        bandwidth in the UE should be carefully justified.    -   Modified PDCCH-related design for the low-cost LTE to simplify        the PDCCH blind decoding and give efficient channel access for a        large number of MTC devices. A reduction in maximum bandwidth        (e.g., 1.4 MHz) decreases PDCCH blind decoding naturally.    -   Protocol simplification including HARQ consideration, MAC, RLC        and RRC protocol. Signaling reduction between low duty cycle MTC        devices and the base station.    -   Transmission modes down-selection to maintain coverage and        balance complexity.

Further considerations on low-cost MTC devices relate to an improvedindoor coverage. A number of applications require indoor deployment ofMachine Type

Communication, MTC, devices, e.g., in an apartment basement, or onindoor equipment that may be close to the ground floor etc. These UEswould experience significantly greater penetration losses on the radiointerface than normal LTE devices. This effectively means that indoorcoverage should be readily available and reliable: i.e., should providea significant improvement on existing coverage.

Additionally, regarding the power consumption of low-cost MTC devices itis noted that many applications require devices to have up to ten yearsof battery life. In this respect, presently available Power Save Modesappear not sufficient to achieve the envisaged battery life. In thisrespect, it is anticipated that further techniques are proposed tosignificantly cut down the power usage of MTC devices e.g., byoptimizing signaling exchanges in the system, in order to realizebattery life of up to ten years.

For improving indoor coverage (for low-cost MTC devices), recentdevelopments have focused on an Enhanced Coverage, EC, mode that isapplicable to UEs e.g., operating delay tolerant MTC applications.Another term is “Coverage Extension”.

The corresponding Work Item in 3GPP Release 12 “Low cost & enhancedcoverage MTC UE for LTE” came to the conclusion that further complexityreduction of LTE devices for MTC can be achieved if additionalcomplexity reduction techniques are supported, as apparent from thetechnical report TR 36.888, v12.0.0, “Machine-Type Communications (MTC)User Equipments (UEs)”, available at www.3gpp.org and incorporatedherein by reference. The technical report TR 36.888 concluded that acoverage improvement target of 15-20 dB for both FDD and TDD incomparison to a normal LTE footprint could be achieved to support theuse cases where MTC devices are deployed in challenging locations, e.g.,deep inside buildings, and to compensate for gain loss caused bycomplexity-reduction techniques. MTC coverage enhancements are nowexpected to be introduced in 3GPP Release 13.

In general, the MTC devices may be low complexity (LC) MTC devices(which basically forces the device to receive a TBS of 1000 bits or lessas a result of buffer size limitations and other implementationlimitations) or enhanced coverage (EC) devices which are supposed tosupport a large number of repetitions.

In other words, LC are Low Complexity devices which are meant to beinexpensive devices with limited buffer sizes/simple implementation etc.whereas the EC devices are the coverage enhanced device that shouldoperate in challenging situations like in basement or far away from thecell center.

The general objective is to specify a new UE for MTC operation in LTEthat allows for enhanced coverage and lower power consumption. Some ofthe additional objectives are given below:

-   -   Reduced UE bandwidth of 1.4 MHz in downlink and uplink.    -   Bandwidth reduced UEs should be able to operate within any        system bandwidth.    -   Frequency multiplexing of bandwidth reduced UEs and non-MTC UEs        should be supported.    -   The UE only needs to support 1.4 MHz RF bandwidth in downlink        and uplink.    -   The allowed re-tuning time supported by specification (e.g., ˜0        ms, 1 ms) should be determined by RAN4.    -   Reduced maximum transmit power.    -   The maximum transmit power of the new UE power class should be        determined by RAN4 and should support an integrated PA        implementation.    -   Reduced support for downlink transmission modes.

The following further UE processing relaxations can also be consideredwithin this work item:

-   -   Reduced maximum transport block size for unicast and/or        broadcast signaling.    -   Reduced support for simultaneous reception of multiple        transmissions.    -   Relaxed transmit and/or receive EVM requirement including        restricted modulation scheme. Reduced physical control channel        processing (e.g., reduced number of blind decoding attempts).    -   Reduced physical data channel processing (e.g., relaxed downlink        HARQ time line or reduced number of HARQ processes).    -   Reduced support for CQI/CSI reporting modes.    -   A relative LTE coverage improvement—corresponding to 15 dB for        FDD—for the UE category/type defined above and other UEs        operating delay-tolerant MTC applications with respect to their        respective normal coverage shall be possible. At least some of        the following techniques, which shall be applicable for both FDD        and TDD, can be considered to achieve this:    -   Subframe bundling techniques with HARQ for physical data        channels (e.g., PDSCH, PUSCH)    -   Elimination of use of control channels (e.g., PINCH, PDCCH)        Repetition techniques for control channels (e.g., PBCH, PRACH,        (E)PDCCH)    -   Either elimination or repetition techniques (e.g., PBCH, PHICH,        PUCCH)    -   Uplink PSD boosting with smaller granularity than 1 PRB    -   Resource allocation using EPDCCH with cross-subframe scheduling        and repetition (EPDCCH-less operation can also be considered)    -   New physical channel formats with repetition for SIB/RAR/Paging    -   A new SIB for bandwidth reduced and/or coverage enhanced UEs    -   Increased reference symbol density and frequency hopping        techniques    -   Relaxed “probability of missed detection” for PRACH and initial        UE system acquisition time for PSS/SSS/PBCH/SIBs can be        considered as long as the UE power consumption impact can be        kept on a reasonable level.    -   Spreading: Spreading refers to spreading of information across        resources including time-frequency domain resources or even        spreading using Scrambling (or Channelization) codes.    -   There can be also other techniques than those listed above.

The amount of coverage enhancement should be configurable per celland/or per UE and/or per channel and/or group of channels, such thatdifferent levels of coverage enhancements exist. The different levels ofcoverage enhancement could mean different level of CE techniques beingapplied to support the CE-device transmission and reception.

Relevant UE measurements and reporting to support this functionalityshould be defined.

For more details, see for example 3GPP RP-141865 “Revised WI: FurtherLTE Physical Layer Enhancements for MTC” sourced by Ericsson, availableat http://www.3gpp.org and incorporated herein by reference.

Notably, coverage enhancements of 15/20 dB for UEs in the EnhancedCoverage mode with respect to their nominal coverage means that the UEshave to be capable of receiving extremely low signal strengths. Thisapplies not only to the initial scanning operation, the cell search andthe cell selection operation but also the subsequent communicationscheme to be performed by the UE. As described above, there will bedifferent levels of CE depending on the network support and UEcapability, e.g., 5/10/15 dB coverage extension.

Early attempts to define the Enhanced Coverage mode have focused onmodifications of the radio transmissions. In this respect, discussionshave focused on repeated transmissions as being the main technique toimprove the coverage. Repetitions can be applied to every channel forcoverage improvement.

An exemplary implementation of these repeated transmissions prescribesthat the same data is transmitted across multiple sub-frames. Yet, itwill become immediately apparent that these repeated transmissions willuse more resources (time-frequency) than what is required for normalcoverage UEs. RANI indicated that the transport block size used fortransmission to the MTC devices will be less than 1000 bits.

The above requirements, a new information message scheduling will benecessary to minimize the system overheard as well as not to affect thesystem of previous releases and legacy UEs served thereby.

BRIEF SUMMARY

One non-limiting and exemplary embodiment provides apparatuses andmethods for an efficient transmission and reception of systeminformation in a wireless network.

In one general aspect, the techniques disclosed here feature anapparatus for receiving system information in a wireless communicationsystem, including a receiver that receives system informationconfiguration information and receives system information inpredetermined subframes of a radio interface, and a controller thatdetermines the predetermined subframes according to the received systeminformation configuration information and controls the receiver toreceive the system information in the predetermined subframes, whereinthe system information configuration information includes a subframescheduling field with a plurality of bits, each bit being associatedwith a subframe and representing whether or not system information is tobe received in that subframe.

It should be noted that general or specific embodiments may beimplemented as a system, a method, an integrated circuit, a computerprogram, a storage medium, or any selective combination thereof.

Additional benefits and advantages of the disclosed embodiments willbecome apparent from the specification and drawings. The benefits and/oradvantages may be individually obtained by the various embodiments andfeatures of the specification and drawings, which need not all beprovided in order to obtain one or more of such benefits and/oradvantages.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a block diagram illustrating current 3GPP architecture formachine type communication;

FIG. 2 is a block diagram illustrating an exemplary architecture of aradio access network in 3GPP LTE;

FIG. 3 is a schematic drawing showing the general structure of a framein 3GPP LTE FDD;

FIG. 4 is a schematic drawing showing the general structure of asub-frame on a downlink component carrier defined for 3GPP LTE;

FIG. 5A is a schematic drawing illustrating association of a bitmap withsystem information scheduling;

FIG. 5B is a schematic drawing illustrating association of a bitmap withsystem information scheduling;

FIG. 6 is a schematic drawing illustrating MBSFN subframe configuration;

FIG. 7 is a schematic drawing illustrating configuration of systeminformation transmission;

FIG. 8 is a block diagram illustrating a receiving apparatus and atransmitting apparatus; and

FIG. 9 is a flow diagram illustrating a receiving and transmittingmethod.

DETAILED DESCRIPTION

The present disclosure relates to transmission and reception of systeminformation in a wireless communication system which is particularlysuitable for transmission and reception of system information formachine type communication such as the MTC in the 3GPP LTE. The systeminformation signaling has been recently discussed in 3GPP and thefollowing aims have been preliminarily agreed on:

-   -   maintain the flexibility similar to the one offered by the        current SIB concept, i.e., the size of the SIBs should not be        fixed.    -   branch from SIB1, i.e., LC/EC UEs receive a separate occurrence        of SIB1 and others (different time/frequency resources). The new        SIB1 is common for EC and LC.    -   transmit SIB1 information separately from other SIBs (in        particular to low cost UEs in normal coverage), if feasible in        terms of overhead and total acquisition time.    -   the scheduling information (time, frequency and MCS/TBS)        allowing acquiring SIB1 for LC/EC UEs could e.g., be carried in        MIB, i.e., dynamic L1 information in PDCCH is not needed.    -   SIB1 for LC/EC UEs could contain scheduling information (time,        frequency and MCS/TBS) allowing acquiring subsequent SIBs        without reading PDCCH.    -   the TB size restriction of 1000 bit for broadcast may be        acceptable, assuming that the network provides separate SIBs        (different time/frequency resources) to LC/EC UEs and legacy        UEs.

If the current mechanism for transmission of system information isapplied for communication applying a large number of repetitions such asMTC communication, each of the SIBs currently used will be transmittedwith approximately 50 times higher repetition rate. These would affect,for instance:

-   -   the acquisition time for the system information by the legacy        UEs if the system information blocks do not overlap and thus,        repetition of the system information would cause longer        transmission delay of the system information block and therefore        also increased the delay of the transmission of the next system        information block,    -   repeated transmissions of the entire system information would        also lead to a huge system load, which may be unnecessary since        the MTC devices does not make use of all information transmitted        in the current system information signaling. Accordingly, the        MTC UEs would receive irrelevant system information.

The reception of the entire system information that would increase powerconsumption in the MTC device.

Thus, the aim of the standardization that the SIB1 should containscheduling information (such as time, frequency and modulation andcoding scheme or transport block size) allowing the acquisition ofsubsequent SIBs without reading Physical Downlink Control Channel(PDCCH) is reasonable since reading PDCCH itself will need similaramount of time/battery and network resources. However, it is currentlynot clear, how this aim is to be achieved. In particular, theacquisition of system information (including one or more SIBS) withoutdynamic scheduling requires the MTC device to know that and where theseSIBs are scheduled. Dynamic scheduling is implemented by means of blinddecoding. In particular, a special identifier for the transmission ofsystem information, SI-RNTI (SI Radio Network Temporary Identity) isprovided. The devices monitor physical downlink shared channel (inparticular, its control part PDCCH) for occurrence of this identifierand upon its detection, the devices read (decode) the correspondingsystem information (System Information format and syntax is specified inthe 3GPP TS 36.331, (for instance, version 12.5.0), Section 5.2, whereasthe physical layer aspects can be found in 3GPP TS 36.212, v12.4.0,Section 5.3.3, both specifications being available at www.3gpp.org).

The scheduling information can be provided to the wireless devices in asystem specification (i.e., the scheduling information is staticallyprovided in the specification). However, this approach does not provideany scheduling freedom which reduces the possibility of efficient andcustomized system information scheduling.

Alternatively, the scheduling information may be providedsemi-statically, for instance in scheduling information such as thescheduling information currently transmitted within SIB 1. However, inthis case it is unclear how the wireless MTC device uses thisinformation in frames and subframes carrying e.g., multimedia broadcastsingle frequency network (MBSFN) communication.

In order to provide a solution for scheduling of system information, theMTC system information could be scheduled in any subframe using acorresponding special RNTI such as MTC-RNTI to indicate that the systeminformation is designated to MTC devices. However, this solution willstill require using of not physically broadcasted channels such as(e)PDCCH or MPDCCH (“e” standing for “enhanced” and “M” for MTC)channels and blind decoding thereof which still results to a high numberof repetitions and delays in system information acquisition times forboth Low Complexity, LC, MTC devices and enhanced coverage, EC, MTCdevices because each LC and EC devices would still need to decode atleast the portions of PDCCH for matching with the specialized identifier(SI-RNTI or MTC-RNTI, respectively).

In order to comply with some of the above aims and to provide efficientsystem information signaling, according to the present disclosure, thesystem information configuration information is transmitted by thenetwork in order to indicate to wireless devices the location of thesystem information. The system information configuration informationincludes a plurality of bits, each bit being associated with a subframeand representing whether or not system information is transmitted inthat subframe.

In an exemplary embodiment, a master information block (MIB) istransmitted (broadcasted) indicating the position of system informationblock (SIB1) for MTC including system information configurationinformation for MTC related system information. The SIB1 for MTC may bea SIB1 different from the SIB1s used for the legacy system information,which has the advantage of avoiding the MTC UEs receiving portions ofSIB not relevant for their operation. However, the present disclosure isnot limited thereby and, in general, the SIB1 may be common to both thelegacy and the low complexity/enhanced coverage UEs including onlyspecific information elements destined for the LC/EC UEs.

The system information (SI) configuration information includes a bitmap(subframe scheduling field), of which each bit indicates for oneparticular subframe whether or not system information is includedtherein. In this embodiment, the system information is systeminformation for the both LC (Low Complexity) and EC (Enhanced Coverage)terminals. However, it is noted that the present disclosure is notlimited to such deployment. Rather, the system information transmissionand reception as described herein may also be applied for conveyingsystem information for either the Low Complexity MTC devices, or onlyfor the Enhanced Coverage MTC devices, in a wireless system as the onlyone approach for conveying the system information.

The bitmap is advantageously a field of bits which take value “0” forsubframes in which no system information is transmitted and take value“1” for subframes in which the system information is transmitted.However, it is clear to those skilled in the art, the assignment of “0”and “1” may also be reversed without departing from the idea.

For instance, the bitmap may include a separate bit for each and everysubframe forming a part of the subframe configuration. In other words,assuming the number of 10 subframes within a radio frame as is the casefor the LTE system, the bitmap has the length of 10 bits for therespective 10 subframes numbered from 0 to 9. However, the presentdisclosure is not limited thereto. Rather, in certain situations it maybe beneficial for the efficiency reasons if the bitmap has less bitsthen the frame has subframes. For instance, in LTE as well as in LTE-Athe first subframe (subframe with number 0) is never used fortransmission of system information. Accordingly, in order to saveresources, the bitmap may have length of 9 bits corresponding torespective subframes 1 to 9. Subframe 0 is used for transmission of anew MIB every fourth frame and for transmission of MIB repetitions inthe remaining frames, i.e., for system information which is broadcasted.The repetitions are not bit-by-bit repetitions but rather differentredundancy versions of the new MIB. No further SIBs are then mapped ontothe same subframe. This is illustrated in FIG. 5A, in which four exampleframes each having 10 subframes are illustrated. Each frame has thefirst subframe dedicated to MIB. Subframes carrying the systeminformation are marked by “x”. The corresponding bitmaps are on theright-hand side: all bitmap have the size of nine bits. The subframescheduling field may thus include a bitmap such as the examples shownabove, having 9 bits. It is noted that the present disclosure is notlimited to a bitmap having a number of bits reflecting (some of the)subframes of one single frame. Rather, the bitmap signaled as thesubframe scheduling field may reflect a plurality of frames. This maymake sense, if a SIB scheduling pattern follows a larger windowrepetition structure. For instance, the bitmap may represent 4 frames,i.e., include all four (in this context sub)-bitmaps shown in FIG. 5Aand thus, may have a length of 4×9=36 bits. However, 4 is only anexample and the number of frames may also differ without departing fromthe present disclosure.

Moreover, the bitmap may be (further) shortened by excluding subframeswhich are not to be used for carrying the system information. Forinstance, the bitmap may be shortened by excluding subframes includingother system information. For instance, subframes scheduled (configured)for legacy coverage system information may be assumed not to carryingsystem information for enhanced coverage system (for instance MTC). Insuch case the bitmap size may be reduced by not including bitscorresponding to subframes configured to carry system information of theco-existing system (system sharing resources). However, in order toachieve this, the position of subframes carrying such parallel systeminformation has to be known to the terminal. This is possible if thescheduling information for the EC and the scheduling information for theLC are carried in the same MIB or SIB1. The EC terminals may also readSIB1 of the LC system in order to receive the scheduling information.

FIG. 5B illustrates an example in which the bitmap size is reduced byexcluding subframe carrying MIB as well as subframes carrying legacycoverage system information (marked as “o”). As can be seen on theright-hand side, the example bitmaps have different sizes. Inparticular, the first bitmap has a size of 7 bits corresponding tosubframe numbers 2, 3, 4, 5, 7, 8, 9 and leaving out the subframes forMIB an LC Ms. The second bitmap has a size of 9 bits corresponding tosubframe numbers 0, 1, 2, 3, 4, 5, 6, 8, 9 and leaving out subframeseven carrying LC SIBs. The third bitmap has a size of 10 bits since itdoes not carry either of MIB or LC Ms. The fourth bitmap has a size ofeight, excluding two bits corresponding to subframes number 4 and 9carrying LC Ms. It is noted that the above bitmaps are also mereexamples. In general, for a system like LTE, in which MIB is transmittedor repeated in each frame, it makes sense to leave out the firstsubframe (and correspondingly each bit in the bitmap) of each frame.However, the present disclosure is not limited to LTE and to systems inwhich MIB is signaled in the first subframe. Thus, FIG. 5B also showsexample bitmaps which do not include and/or leave out any MIB-subframe.As also described with respect to FIG. 5A, FIG. 5B also shows 4examples, each of which illustrates a bitmap that may be transmitted asthe scheduling subframe field -reflecting one single frame. Therepetition and location of such frames may be determined by furtherscheduling parameters such as offset and repetition period.

However, the present disclosure also includes a scheduling subframefield representing subframes more than one frames, i.e., a bitmap withbits corresponding to subframes of more than one frame. For instance,first two frames of FIG. 5B may be represented by a bitmap with 7+9=16bits corresponding to the first two bitmaps with 7 and 9 bitsrespectively.

The subframes in which the system information is transmitted may stillbe used also for unicast transmission of other data. In particular, inorder to reduce overhead costs by scheduling of system information, itmay be beneficial to predefine certain number of physical resourceblocks as well as their position in the resource grid of a subframe usedfor system information if that subframe is configured to carry thesystem information. For example, in subframes configured to carry SI,central six physical resource blocks without applying frequency hoppingmay be used to carry the SI. This is only an example and alternativelythe predefined location may include central six physical resource blockswith applying frequency hopping. However, other configurations areapplicable including other amount of physical resource blocks and otherthan central location.

The present disclosure is not limited to this configuration, and inorder to enable more flexibility in scheduling the system information,the frequency allocation may also be signaled within the SIconfiguration information. For instance, the number and/or location ofthe frequency resources may be signaled as well as whether or notfrequency hopping is applied. Alternatively, the number N the locationof the frequency resources may be known and the signaling may onlyinclude whether or not frequency hopping is applied. Stillalternatively, the usage of frequency hopping may be predefined as wellas the location of frequency resources for a particular amount offrequency resources, whereas the number of frequency resources issignaled. Other configurations of predefined and signaled schedulinginformation are possible.

For example, the frequency location and hopping information forscheduling MTC SIs (each SI containing one or more SIBs) is contained ina separate scheduling information block which may reside inside the SIB1or even as a separate block scheduled from SIB1. Another possibility isto use the scheduling information (e.g., either/both frequency and timedomain scheduling), or a derivation (e.g., an offset) thereof, used toschedule SIB1 (for MTC). In particular, SIB1 for MTC can be scheduledusing MIB wherein some bits in MIB indicate a combination in MIB, thecombination indicating possibilities of:

-   -   CE Support=Yes/No    -   Possible SIB1 (MTC) sizes=X/Y/Z bits    -   Possible subframes used to transmit SIB1 (MTC).

An example of such combinations is shown in the table below (using a 2bit combination):

Combination Subframes Index Size of MTC SIB1 used for MTC SIB1 00 No CESupport 0 01 newSIB1-SizeXbits Sf#4 10 newSIB1-SizeYbits Sf#4, 5 and9 11newSIB1-SizeZbits Sf# 3, 4, 6, 7, 8 and 9

In this table, the first column shows the bits indicating one of the 4possible combinations. The second column shows size of the new SIB1(i.e., SIB1 for the other system like MTC) and the third column showsthe subframes of a frame possibly used to transmit the new SIB 1. Therows of the table thus show the respective possible configurations.

However, it is noted that there may be more than 4 possible combinationssignaled, using more than 2 bits.

For instance, a higher bit combination such as a 5 bit combination inMIB could be used. Moreover, such combinations may also include otherparameters than the

SIB1 size and the subframes in which SIB1 is scheduled. Alternatively orin addition to these parameters, the combination may indicate frequencyresources/hopping pattern etc. corresponding to each of the abovecombinations.

SIB1 may then carry the bitmap as described above indicating in whichsubframes further system information is carried. The bitmap already mayleave out bits corresponding to subframes for SIB1 scheduling which areindicated, for instance, by the combination as exemplified in the tableabove.

Therefore, the derivation of SI resources may depend on (or be derivedfrom) the MTC SIB1 scheduling which in turn is being scheduled from MIB.The derivation information (e.g., time/frequency offset) for SIresources could be signaled in MTC SIB1 itself

Alternatively, or in addition, if there are subframes configured formultimedia broadcast such as MBSFN in LTE like systems, the systeminformation will not be carried in such subframes. Correspondingly, thebitmap size may be reduced by not including bits corresponding tosubframes configured for multimedia broadcast. It is noted thatmultimedia broadcast subframes may be excluded if their position isknown from other signaling information.

MBSFN subframes are configured semi-statically in LTE, i.e., via RRCprotocol. This configuration specifies how periodically the MBSFNsubframes appear (e.g., every X frames) and where does the subframemapping start from (offset).

In particular the physical layer scheduling of MBSFN subframes isspecified in SIB2 within an information element (IE)mbsfn-SubframeConfigList, further including MBSFN-SubframeConfig IEwhich has the following format:

MBSFN-SubframeConfig ::= SEQUENCE {  radioframeAllocationPeriodENUMERATED {n1, n2, n4, n8, n16, n32},  radioframeAllocationOffsetINTEGER (0..7),  subframeAllocation CHOICE {   oneFrame  BIT STRING(SIZE(6)),   fourFrames  BIT STRING (SIZE(24))  } }in which the IE fourFrames is a bit-map indicating MBSFN subframeallocation in four consecutive radio frames, “1” denotes that thecorresponding subframe is allocated for MBSFN. The bitmap is interpretedas follows: In FDD: Starting from the first radio frame and from thefirst/leftmost bit in the bitmap, the allocation applies to subframes#1, #2, #3, #6, #7, and #8 in the sequence of the four radio-frames. InTDD: Starting from the first radio frame and from the first/leftmost bitin the bitmap, the allocation applies to subframes #3, #4, #7, #8, and#9 in the sequence of the four radio-frames. The last four bits are notused. Uplink subframes are not allocated. The subframes of a frame arenumbered from #0 to #9.

In the IE oneFrame, “1” denotes that the corresponding subframe isallocated for MBSFN. The following mapping applies for FDD: Thefirst/leftmost bit defines the MBSFN allocation for subframe #1, thesecond bit for #2, the third bit for #3, the fourth bit for #6, thefifth bit for #7, and the sixth bit for #8; for TDD: The first/leftmostbit defines the allocation for subframe #3, the second bit for #4, thethird bit for #7, the fourth bit for #8, and the fifth bit for #9.Uplink subframes are not allocated. The last bit is not used.

As is indicated by the term “CHOICE” in the syntax above, only one ofthe fourFrames IE and fourFrames IE is used.

The IEs radioFrameAllocationPeriod and radioFrameAllocationOffset definein which frames the MBSFN subframes are scheduled. In particular, radioframes that contain MBSFN subframes occur when equation SFN moduloradioFrameAllocationPeriod=radioFrameAllocationOffset is satisfied.Value n1 for radioframeAllocationPeriod denotes value 1, n2 denotesvalue 2, and so on. When the IE fourFrames is used forsubframeAllocation, the equation defines the first radio frame referredto in the description below. Values n1 and n2 are not applicable whenfourFrames is used.

The IE subframeAllocation defines the subframes that are allocated forMBSFN within the radio frame allocation period defined by theradioFrameAllocationPeriod and the radioFrameAllocationOffset.

An exemplary configuration of MBSFN is illustrated in FIG. 6 . In thisexemplary configuration, each 8th radio frame is configured for MBSFNtransmission, starting with the third frame corresponding to offset oftwo. The subframes are specified by the bitmap “110000” (6 bitscorresponding to subframes #1, #2, #3, #6, #7, and #8 respectively)which specifies that subframes #1 and #2 in the configured frames (the10 subframes in a frame are number from 0 to 9) are used for the MBSFNtransmission.

The above described subframe configuration for multimedia broadcast inLTE may be received by the terminal and used to determine MBSFNsubframes and to exclude the determined MBMS subframes from amongsubframes which are to be used for conveying the system information forMTC. Accordingly, the system information configuration information doesnot need to include bits corresponding to subframes configured for MBSFN, thus reducing the SI overhead.

However, it may be beneficial for some terminals not to read (decode)the MBSFN signaled in SIB2 for instance in order to reduce powerconsumption caused by receiving and the decoding of SIB2 of the legacysystem in addition to receiving and decoding of the system informationfor the enhanced coverage system.

In order to enhance configurability of system information signaling,according to an embodiment, a subframe scheduling field application bit(abbreviated as “U-bit” meaning “universality bit”) is provided. TheU-bit indicates whether the subframe scheduling field is to beunderstood universally, i.e., without considering MBSFN subframeconfiguration or whether the subframes configured for MBSFN are to beexcluded. For instance, if U-bit is set to TRUE (e.g., logical “1”), itmeans that the subframe scheduling field (bitmap) is a universal bitmapand is applicable irrespectively of the MB SFN configuration in the celland therefore the UE (MTC device) does not need to acquire/use theMBSFN-SubframeConfig. On the other hand, if the U-bit is set to FALSE(e.g., logical “0”), it means that the subframe scheduling field(bitmap) is not a universal bitmap and the MTC device must also acquirethe IE MBSFN-SubframeConfig in order to determine the position ofsubframes configured for MTC SI (EC SI) in order to avoid attempts toreceive MTC SI on subframes that are not carrying MTC SI since theyalready carry MB SFN.

Accordingly, with one single bit it may be indicated whether the sameconfiguration applies for SI transmission in frames configured as MBSFNsubframes as well. In case the subframe scheduling field is universal,i.e., valid for any subframes also including multimedia broadcast, it isup to the network to ensure that no collision occurs, i.e., that thescheduling information is not scheduled to the same subframes as themultimedia broadcast. MTC device just assumes that all the subframes(irrespective of and with or without the knowledge of if the subframesbelong to the frames carrying MBSFN subframes or not) indicated by thesubframe scheduling field for the MTC SI carry the MTC SI.

In case the subframe scheduling field is not universal, i.e., it can beonly correctly interpreted after reception of the multimedia broadcastconfiguration, it is to be ensured that the terminals receive both themultimedia broadcast configuration and the subframe scheduling field. Inorder to avoid increased battery consumption which would be caused byattempts to receive and decode system information carrying themultimedia broadcast configuration in the legacy system, the multimediabroadcast configuration may be included into the EC specific systeminformation. For instance, the IE mbsfn-SubframeConfigList may beincluded into the MTC-specific SIB such as MTC SIB 1.

Accordingly, based on the U-bit value, the MTC device may exactly knowwhere the MTC SI will be transmitted and therefore avoid unnecessaryreception attempts, thereby saving battery.

For instance, when the value of the U-bit is FALSE, then the wirelessdevice (such as MTC device) performs the following calculation to findout which subframes in frames carrying MBSFN subframes are carrying MTCSI. Let A be a bitmap corresponding to the subframe scheduling field forthe MTC SI and B be an extended bitmap corresponding to MBSFNconfiguration as described above for LTE. It is noted that in thisexample the format of both bitmaps may cover either one or four framesas exemplified above for the MBSFN configuration. Accordingly, thebitmap A may be 10 or 40 bits long -describing subframes of one or 4frames, respectively. Bitmap B may have the same format, which may begenerated by taking the 6 or 24 bits as described above belonging to theMBSFN configuration and inserting “0” on the positions of correspondingsubframes not included into the bitmap (i.e., corresponding to thenon-MBSFN subframe positions). For instance, A=0101010101 andB=0110000000 in their extended format (inserting 0s at positions 0, 4, 5and 9), covering all subframes of a single frame. In order to determinethe location of the SI, logical AND is applied between the frames withSI configured and frames without MB SFN configured, corresponding to AAND (NOT(B)) which is for the above example (0101010101) AND (NOT(0110000000))=0101010101 AND 1001111111=0001010101.

Therefore, in normal frames the SI is carried in subframes #1, #3, #5,#7, #9 (i.e., bitmap A) and in MBSFN frames in subframes #3, #5, #7, #9(A AND (NOT(B))).

A possible ASN structure for this embodiment may look as shown in thefollowing:

-   -   Similarly to the MTSFN subframes signaling, the configuration        for system information may be carried in system information        within a container IE “MTCSISubframeConfig”. As is clear to        those skilled in the art, the name of this IE is only exemplary        and any other name may be used instead. In this example, the IE        MTCSISubframeConfig defines subframes that are reserved for MTC        SI transmission in downlink on MTC specific bandwidth as        follows:

-- ASN1START MTCSI-SubframeConfig ::= SEQUENCE { radioframeAllocationPeriod ENUMERATED {n1, n2, n4, n8, n16, n32}, radioframeAllocationOffset INTEGER (0..7),  firstBitmapSolution1 BITSTRING (SIZE(10)),  universalUse ENUMERATED {True, False}, mbsfn-SubframeConfig MBSFN-SubframeConfig OPTIONAL -- Cond universal }-- ASN1STOP

The MTCSI-SubframeConfig IE includes further IEs. The meaning of the IEsradioFrameAllocationPeriod and radioFrameAllocationOffset is the similaras for the corresponding, above described MBSFN IEs. In particular, theIEs radioFrameAllocationPeriod and radioFrameAllocationOffset define inwhich frames the SI subframes are scheduled.

IE firstBitmapSolution1 corresponds to the subframe schedulinginformation field described above and is a bitmap with 10 bits forrespective 10 subframes of a frame. As described above, the bitmap maybe shorter than the number of subframes in a frame.

IE universalUse corresponds to the above described U-bit and indicateswhether or not the IE firstBitmapSolution1 applies continuously, i.e.,for all subframes of the frames indicated by the allocation period andoffset. The IE universalUse can take two Boolean values: True or False.If the IE universalUse has the value False, then the wireless devicereceiving the bitmap needs to determine (e.g., calculate by logicaloperations as described above) which subframes in the frames carryingalso MBSFN subframes will carry the MTC SI. This is performed in thisexample by reading the following IE mbsfn-SubframeConfig which isdescribed above and which indicates the configuration of the MBSFNframes including allocation period, offset and bitmap.

In other words, if the IE universalUse has the value False, then the IEmbsfn-SubframeConfig is present. If on the other hand the IEuniversalUse has the valueTrue, then the IE mbsfn-SubframeConfig may notbe present.

The conditional presence set to “universal” in the ASN syntax abovemeans that this field (IE mbsfn-SubframeConfig) is mandatory presentwhen the field universalUse has the value False.

It is noted that this example shows the inclusion of the MBSFNconfiguration (scheduling) directly into the system informationconfiguration information (corresponding to the IEMTCSI-SubframeConfig). However, the present disclosure is not limited bythis example. The ASN syntax may include the U-bit (universalUse) andnot include the MBSFN configuration. In such case, as described above,the MTC device may determine the MBSFN configuration by reading thecorresponding system information (such as IE mbsfn-SubframeConfigList inSIB2 in the case of the LTE legacy system).

Including the MBSFN configuration into the system informationconfiguration information has the advantage of not requiring the MTCdevice to monitor resources for SIB1 by using the RNTI-SI. On the otherhand, including the MBSFN configuration into the system informationconfiguration information requires additional signaling overhead.

FIG. 7 shows frames carrying MBSFN subframes i.e., frames with sequenceframe number (SFN) equal to 2, 10 and 18 (frame number and positions arederived from the IEs radioFrameAllocationPeriod andradioFrameAllocationOffset as described above). Further, the figureshows four types of subframes:

-   -   Non MBSFN subframes (subframes with number 0, 4, 5 and 9 within        the frame 10 in the figure) that cannot be used for        eMBMS/MBMS/MBSFN purpose (i.e., for multimedia broadcast        transmission),    -   Subframes that may be configured for eMBMS/MBMS purpose/MBSFN        (subframes with number 1, 2, 3, 6, 7 and 8),    -   Subframes that are actually configured for eMBMS/MBMS/MBSFN        purpose (1, 2) in this example, which is given by the        oneFrame/fourFrame field as described above.    -   Subframes that are configured for transmission of the MTC SI        (subframes with numbers 3, 5, 7, and 9), which may be indicated        in the SI configuration information as described above.

Also, the diagram shows as an example that the MTC SI(s) are scheduledin the central 6 PRBs per default so that no additional frequencyscheduling is necessary. It is noted that FIG. 7 is a mere example of aconfiguration.

In accordance with another, second embodiment, two separate bitmaps withtwo different respective formats are provided within the SIconfiguration information, one for normal frames (frames not carryingMBSFN subframes) and another one for frames carrying MB SFN subframes.One of the advantages of this embodiment is that it is simpler for theterminal, since the UE does not need to receive the MBSFN information,perform some bitwise operation as exemplified above etc. It merelyapplies the configurations as they apply to different set of frames,i.e., to the frames/subframes corresponding to the two bitmapformats/configurations.

The MTC device does not need to know anything about the MBSFNconfiguration. It merely applies the format based on a configuration(e.g., format1 on even subframes and format2 on odd subframes) which isalso signaled within the SI configuration.

In particular, the length of a normal-frame bitmap may be 10 bits (or 9bits when assuming that subframe #0 is never used for MTC SItransmission) whereas the length of the bitmap for frames carrying MBSFN subframes (MTCSI-subframeAllocationbitmap) may be the same as theMBSFN scheduling described above. In the following, an example of such abitmap is shown:

-- ASN1START MTCSI-subframeAllocation CHOICE {   oneFrame BIT STRING(SIZE(6)),   fourFrames BIT STRING (SIZE(24))  } -- ASN1STOP

As a further optimization, a ‘Q-bit’ bit may indicate whether or not thecorresponding bits in the first bitmap apply also to subframes #0, #4,#5, #9 (in FDD) and subframes #0, #1, #5, #6 (in TDD; either DL orspecial subframes) in frames pointed to by the information elementincluding the second bitmap configuration. The above mentioned subframes#0, #4, #5, #9 (in FDD) and subframes #0, #1, #5, #6 (in TDD) aresubframes which are never (i.e., in no frame) used to transmit MBSFNdata.

The second solution always signals two separate bitmaps one for normal(non-MBSFN) frames and other for frames carrying MBSFN subframes. Thesecond bitmap (for frames carrying MB SFN subframes) does not talk aboutsubframes #0, #4, #5, #9 (in FDD) and subframes #0, #1, #5, #6 (in TDD).So, using the 1 bit information, the network can indicate whether or notthe first bitmap applies also to these subframes of a frame carryingMBSFN subframes.

Alternatively, an interpretation may be defined for instance in astandard, according to which the UE has to assume that the correspondingbits in the first bitmap applies also to subframes #0, #4, #5, #9 (inFDD) and subframes #0, #1, #5, #6 (in TDD; either DL or Specialsubframes) in frames pointed by the second bitmap configuration.

An exemplary syntax for the SI configuration information is shown below.The configuration for system information according to this secondembodiment may also be carried in system information within a containerIE “MTCSI-SubframeConfig”.

The IE MTCSI-SubframeConfig defines subframes that are reserved for MTCSI transmission in downlink on a MTC specific bandwidth.

-- ASN1START MTCSI-SubframeConfig ::=  SEQUENCE {  firstBitmap BITSTRING (SIZE(10)),  secondBitmap SecondBitmap } SecondBitmap ::=SEQUENCE {  radioframeAllocationPeriod   ENUMERATED {n1, n2, n4, n8,n16, n32},  radioframeAllocationOffset   INTEGER (0..7), subframeAllocation    CHOICE {   oneFrame   BIT STRING (SIZE(6)),  fourFrames   BIT STRING (SIZE(24))  } } -- ASN1STOP

The SI configuration above includes a first bitmap field “firstBitmap”which has a length of 10 bits. It is noted that this is only anexemplary length of the bitmap corresponding to the number of subframesper frame. However, as described above, some subframes may be left outas well as the corresponding bitmap bits and thus the first bitmap maybe shorter than the number of subframes per frame. The informationelement firstBitmap is applied to frames to which secondBitmap is notapplicable.

The second bitmap is included in an IE secondBitmap which includes notonly the bitmap itself (subframe scheduling field) but also furtherconfiguration information -in this example it is the allocation periodand offset. The IE secondBitmap thus tells exactly on which frames andsubframes SI MTC will be provided. Interpretation of individual fields(radioframeAllocationPeriod, radioframeAllocationOffset, oneFrame andfourFrames) is the same as in the MBSFN-SubframeConfig described in theabove first embodiment.

In the above example, the configuration of the secondBitmap includes abitmap (in the field oneFrame or in the field fourFrames) which isshorter (in terms of a number of bits) than the first bitmap if thelength of 6 bits is taken. In particular, the bitmap in the secondBitmapIE follows the lengths of the MBSFN configuration IEs, i.e., 6 and 24subframes. However, the length of the second bitmap may also be 24 bits.

Accordingly, in the above example, the second bitmap does not addresssome subframes preknown to the UE e.g., subframes 0, 4, 5, 9 (for FDD)which cannot carry MBSFN frames. However, it is noted that the presentdisclosure is not limited to such configuration. The second bitmap mayalso address these frames and not address others (for instance frame 0because of MIB signaling or other examples mentioned in connection withthe first embodiment).

As described above, a Q-bit may also be part of the SI configurationinformation as is exemplified in the following ASN syntax.

-- ASN1START MTCSI-SubframeConfig ::=  SEQUENCE {  firstBitmap  BITSTRING (SIZE(10)),  secondBitmap   SecondBitmap,  q-Bit  ENUMERATED{True, False} } SecondBitmap ::= SEQUENCE {  radioframeAllocationPeriod  ENUMERATED {n1, n2, n4, n8, n16, n32},  radioframeAllocationOffset  INTEGER (0..7),  subframeAllocation    CHOICE {   oneFrame  BIT STRING(SIZE(6)),   fourFrames  BIT STRING (SIZE(24))  } } -- ASN1STOP

The Q-Bit indicates whether or not the bits in the firstBitmap (#0, #4,#5, #9 in FDD and subframes #0, #1, #5, #6 in TDD) apply also to thecorresponding subframe position of the secondBitmap. Accordingly, withthe Q-bit set to True, the subframes not addressed by the secondbitmap's bits may still be used for transmission of SI.

Similarly as U-bit, the IE q-bit can take two Boolean values: True orFalse. If the IE q-bit has the value False, then the first bitmap isonly applicable to the frames not indicated in the second configurationcarried in the IE secondBitmap. These may advantageously be thenon-MBSFN frames. If, on the other hand, the IE q-bit has the valueTrue, the first bitmap is also applicable to subframes not associatedwith any bits in the second bitmap (carried in oneFrame or fourFramesfields of the IE secondBitmap) which subframe positions (from 0-9) arebeing referred in by the secondBitmap may be specified and could, as anexample, correspond to non-MBSFN subframes (i.e., subframes #0, #4, #5,#9 (in FDD) and subframes #0, #1, #5, #6 (in TDD)).

Thus, if the Q-bit is set to True, then a user device may determine thesubframes carrying system information by applying logical OR between thesecond bitmap and the first bitmap as is illustrated in the followingexample: Assume the first bitmap (C) being 0001010110 and the secondbitmap (D) being 010101. Then a bitmap C′ is obtained by setting allpositions of C except for the positions 0, 4, 5, 9 (positions notcovered by the second bitmap) to zero resulting in C′ =0001000010. Thesecond bitmap D is extended to cover the number of subframes in theframe (here 10) by inserting “0” on the positions (0, 4, 5, 9) notcovered by the second bitmap. This results in the second bitmap D′ being0010001001. Then a logical (bitwise) OR (non-exclusive) is performedbetween C′ and D′ resulting in 0001000010 OR 0010001001=0001001011 whichmeans that the SI information is transmitted in the subframes withnumber 3, 6, 8 and 9 on the frames indicated by the secondBitmap; and onall other frames on subframes with number 3, 5, 7 and 8.

It is noted that the meaning of True and False may also be reversed.Moreover, it is noted that the bitmap D may also have a length of 24bits as exemplified in the syntax above. In such case the bitmap D′ isformed by inserting the zeros in positions of subframes 0, 4, 5, and 9in each of the 4 frames represented by the 24-bit bitmap, obtaining inthis way 40 bits. The 10-bit long second bitmap C would be repeated fourtimes, resulting also in 40 bits. Then, similarly as described above,bitmap C′ would be formed, also maintaining a length of 40 bits.

The above syntax and bitmap lengths are exemplary. As also alreadydescribed above, any other lengths may be selected, depending on thenumber of subframes per frame and the number of subframes which have noassigned corresponding bit in the bitmap.

The present disclosure may provide several advantageous effectsespecially when applied to MTC SIB signaling in addition to aco-existing legacy system SIB signaling. In comparison with the currentLTE SIB signaling, the present disclosure avoids introducing huge systemload due to repetitions on a channel which has to be decoded blindly.The use of the channels on which blind decoding is to be applied such as(e)PDCCH/MPDCCH is avoided i.e., no dynamic scheduling for SItransmission is required. Moreover, legacy UEs are not affected so thatthey can still operate without any modifications. On the other hand,with the present disclosure, provisioning of static schedulinginformation in specification is not required.

In the present disclosure, an MTC device behavior is designed whichexactly knows how the semi static scheduling information is to be usedin MBSFN and normal frames/subframes. Among other advantages, thisenables reducing the UE power consumption by restricting the UEacquiring SIs only in subframes that really carry the said SI.

In the above examples, the system information configuration informationspecified the location of the resources on which the SI is to betransmitted unambiguously. This means that the wireless devices do notneed to attempt blind decoding in order to read the system informationbut rather know exactly, where and when to read it. Accordingly, if theabove disclosure is applied for MTC SI signaling, the MTC devices maysave battery by not trying blind decoding and thus no special RNTI forthe MTC SI is necessary either.

However, in general, the position of the system information does nothave to be precisely specified. In order to limit the power consumption,the opportunities for blind decoding may be merely reduced rather thanfully specifying the position for reading/decoding the resources.

In particular, there may be predefined rules according to which thesystem information is not mapped on the resources (subframes):

-   -   onto which physical broadcast channel is mapped, for instance        the MIB and/or MTC-SIB1; and/or    -   configured for multimedia broadcast (such as MBSFN, i.e.,        subframes in frames carrying MBSFN subframes); and/or    -   scheduled for legacy SI transmission (using SI-RNTI, i.e., blind        decoding).

In other words, the network schedules (MTC) system information similarlyto the legacy system, i.e., dynamically using a separate identifierMTC-RNTI. The MTC terminals that attempt blind decoding by attempting todetect occurrence of the MTCRNTI in the (e)PDCCH or the equivalentchannel for MTC monitored resources (basically CRC of (e)PDCCH/MPDCCHmasked with MTC-RNTI) and upon detection of the MTC-RNTI read the MTC SIon that resources. In accordance with the above example, the terminalsmay reduce the number of monitored resources by excluding any ofMTC-SIB1 subframes, legacy SI subframes, MBSFN subframes or the like.

Another issue concerning the attempts to decode such unnecessary tryingcomplicates how it counts ‘max number of failed soft combining attempts.This is required in order to not erroneously count/conclude that themaximum number of failed soft combining attempts have been exceeded.This determination of exceeding the maximum number is used to notifyhigher layers that the system information could not be acquired.

MTC SI, similarly to the MTC data are to be transmitted with a largeamount of repetitions in order to extend the coverage for the MTC systemby ensuring correct reception even in bad channel conditions asexplained in the background section.

The repetitions are not necessarily repetitions of the same codedblocks. Rather, the data before encoding is the same, but therepetitions generally represent possibly different encodings of the samedata (i.e., different redundancy versions for HARQ retransmissions).This means that the repetitions may belong to other redundancy versions.The receiver then tries to combine received data gained by repetitionsand decode it. The more repetitions are received, the higher is theprobability of correct decoding. After a predetermined number ofdecoding attempts, the reception is considered as failed and the higherlayers are notified as is done in MAC sublayer upon exceeding MaximumHARQ retransmissions described in section 5.4.2.2 of 3GPP TS 36.321,v12.5.0, “Evolved Universal Terrestrial Radio Access (E-UTRA); MediumAccess Control (MAC) protocol specification” available at www.3gpp.org.

If the system information is scheduled semi-statically and unambiguouslyas described in the above disclosure, the terminal has the accurateinformation concerning the location and number of repetitions of thesystem information repetitions scheduled. The number of repetitionscould be specified or configured in system information. UE knows fromthe scheduling info which SIs is/are being transmitted within whichSI-windows. UE knows from the MTC Scheduling info how often theSI-window for SIX will come, how long is the SI-Window etc. Thus, theterminal is capable of correctly determining when the predeterminednumber of decoding attempts failed. However, in the case of blinddecoding, the terminal may count some SI reception attempts (when MTC SIwas not even being transmitted) and thus, count the decoding attemptsincorrectly. If not counted correctly, the UE may prematurely quit toacquire the said system information and thus fail to avail theservice(s) of the network which could include also camping/selecting acell.

In other words, the present disclosure provides an apparatus forreceiving system information illustrated in FIG. 8 and operable in awireless communication system such as the one illustrated in FIGS. 1 and2 . The apparatus (receiver, wireless device as illustrated also in FIG.2 ) 800A comprises: a receiving unit 820 for receiving systeminformation configuration information and for receiving systeminformation in predetermined subframes of a radio interface; and acontrol unit 810 for determining the predetermined subframes accordingto the received system information configuration information and forcontrolling the receiving unit 820 to receive the system information inthe predetermined subframes, wherein the system informationconfiguration information includes a subframe scheduling field with aplurality of bits, each bit being associated with a subframe andrepresenting whether or not system information is to be received in thatsubframe.

In particular, the wireless device 800A may be a mobile terminal in acellular system such as LTE or LTE-A, in which system information istransmitted by means of the RRC protocol messages. The receiving unit820 receives the SI configuration and passes it to the control unit 810which then controls the receiving unit 820 to receive the systeminformation according to that configuration. Receiving here meansphysically receiving the wireless signal and decoding the informationtransmitted.

The present disclosure also provides an apparatus 800B for transmittingthe system information in the wireless communication system. Theapparatus 800B may be a network node such as a base station or morespecifically an (e)NB in the LTE system. The network node 800B comprisesa configuration unit 860 for configuring subframes to carry or not tocarry system information, to generate a system information configurationinformation indicating the configuration, and for controlling atransmitting unit 870 to transmit the system information in theconfigured subframes, wherein the transmitting unit 870 serves fortransmitting system information configuration information and fortransmitting system information in the configured subframes of a radiointerface; wherein the system information configuration informationincludes a subframe scheduling field with a plurality of bits, each bitbeing associated with a subframe and representing whether or not systeminformation is to be received in that subframe.

The network node 800B configures the transmission of the systeminformation according to the type of the cell and the features supportedby the cell as is also the case for the system information transmittedin the 3GPP LTE or LTE-A or UMTS or any other known system. The featuresof the cell may include support for MTC—either of or both low complexity(LC) and coverage enhancement (EC) and the system information related tothese features.

Advantageously, the number of bits of the system informationconfiguration information associated with respective subframes is lessthan or equal to the number of subframes in a radio frame; none of thebits is associated with at least one of:

-   -   subframes used for reception of system information configuration        information,    -   subframes used for a physical broadcast channel, subframes        configured for multimedia broadcast operation; and the system        information is transmitted by the network node 800B (and        correspondingly also received by the wireless device 800A) only        on subframes indicated by the bits in the subframe scheduling        field of the system information configuration information.

For instance, the system information configuration information istransmitted (from the network node 800B) and received (by the wirelessdevice 800A) either within a master information message of a radioresource control protocol carried on a physical broadcast channel orwithin a system information message of the radio resource controlprotocol scheduled in the master information message, and the systeminformation configuration information further comprises an indication ofthe frequency resources for the system information including at leastone of a location and/or number of physical resource blocks reserved forthe system information, and/or whether or not frequency hopping isapplied.

The apparatus 800A (wireless device) may be a machine typecommunication, MTC, terminal and said system information may be systeminformation for MTC. Advantageously, none of the bits in the subframescheduling field is associated with subframes carrying systeminformation for other type of communication.

For example, the system information configuration information furthercomprises a subframe scheduling field application indicator forindicating whether or not a multimedia broadcast scheduling informationis to be used; the control unit 810 of the receiver is configured, whenthe subframe scheduling field application indicator has a first value,to

-   -   receive the multimedia broadcast scheduling information        indicating subframes used for multimedia broadcast        communication;    -   determine the predetermined subframes in accordance with the        multimedia broadcast scheduling information by excluding the        subframes used for multimedia broadcast communication; and    -   not to receive or take into account the multimedia broadcast        scheduling information when the subframe scheduling field        application indicator has another value different from the first        value.

Correspondingly, the configuration unit 860 is configured to set thesubframe scheduling field application indicator and the corresponding SIconfiguration information accordingly.

The multimedia broadcast scheduling information may include a subframescheduling field with a plurality of bits, each bit being associatedwith a subframe and representing whether or not multimedia broadcast isto be transmitted in that subframe.

The control unit 810 of the wireless device is then advantageouslyconfigured to determine the predetermined subframes by applying alogical AND between bits of a bitmap representing the subframes in whichthe system information is to be received and the subframes in which themultimedia broadcast is not transmitted.

Alternatively, the system information configuration informationincludes:

a first subframe scheduling field and a second subframe scheduling filedof which each includes subfields for some respective subframes; and

-   -   scheduling information indicating to which frames the second        subframe scheduling field applies,    -   the second subframe scheduling field is applied to the frames        indicated by the scheduling information whereas the first        subframe scheduling field is applied to any other frames.

For example, the second subframe scheduling field has no bits associatedwith some predefined subframes; and the system information configurationinformation includes a first bitmap application bit for indicatingwhether or not the bits of first subframe scheduling field associatedwith said predefined frames are to be applicable for the framesindicated in the scheduling information.

For any of the above described examples, a master information messagetransmitted on a physical broadcast channel may include schedulinginformation concerning subframe scheduling of a first system informationwhich includes the system information configuration information, andnone of the bits of the subframe scheduling field is associated withsubframes indicated as carrying the first system information in saidscheduling information.

The scheduling information may consist of a predefined number ofpredefined combinations of at least two of: first system informationsize, subframes in which the first system information can be scheduled,application of frequency hopping, frequency hopping pattern andfrequency allocation.

Further features as described above in detail may be featured by thewireless device, network node and the system information configurationinformation format.

The present disclosure further provides a method 900A for receivingsystem information in a wireless communication system (the interfaceformed by the wireless channel is illustrated by the vertical dashedline 990) as illustrated in FIG. 9 . The receiving method 900A includesthe steps of receiving system information configuration information 930and receiving system information 960 in predetermined subframes of aradio interface; and determining 940 the predetermined subframesaccording to the received system information configuration informationand controlling 940 the receiving of the system information to takeplace in the predetermined subframes, wherein the system informationconfiguration information includes a subframe scheduling field with aplurality of bits, each bit being associated with a subframe andrepresenting whether or not system information is to be received in thatsubframe.

The present disclosure also provides a method 900B for transmitting thesystem information in the wireless communication system comprising thesteps of configuring 910 subframes to carry or not to carry systeminformation and to generate a system information configurationinformation indicating the configuration as well and controlling thetransmitting unit to transmit the system information in the configuredsubframes, and further comprising the steps of transmitting 920 thesystem information configuration information and transmitting 950 thesystem information in the configured subframes of a radio interface,wherein the system information configuration information includes asubframe scheduling field with a plurality of bits, each bit beingassociated with a subframe and representing whether or not systeminformation is to be received in that subframe.

In another general aspect, the techniques disclosed here feature anapparatus for transmitting system information in a wirelesscommunication system comprising: a configuration unit for configuringsubframes to carry or not to carry system information, to generate asystem information configuration information indicating theconfiguration, and for controlling the transmitting unit to transmit thesystem information in the configured subframes, wherein a transmittingunit for transmitting system information configuration information andfor transmitting system information in the configured subframes of aradio interface; wherein the system information configurationinformation includes a subframe scheduling field with a plurality ofbits, each bit being associated with a subframe and representing whetheror not system information is to be received in that subframe.

In another general aspect, the techniques disclosed here feature amethod for receiving system information in a wireless communicationsystem comprising: receiving system information configurationinformation and for receiving system information in predeterminedsubframes of a radio interface; and determining the predeterminedsubframes according to the received system information configurationinformation and for controlling the receiving of the system informationto take place in the predetermined subframes, wherein the systeminformation configuration information includes a subframe schedulingfield with a plurality of bits, each bit being associated with asubframe and representing whether or not system information is to bereceived in that subframe.

In one general aspect, the techniques disclosed here feature a methodfor transmitting system information in a wireless communication systemcomprising: configuring subframes to carry or not to carry systeminformation, to generate a system information configuration informationindicating the configuration, and for controlling the transmitting unitto transmit the system information in the configured subframes, whereintransmitting system information configuration information and fortransmitting system information in the configured subframes of a radiointerface; wherein the system information configuration informationincludes a subframe scheduling field with a plurality of bits, each bitbeing associated with a subframe and representing whether or not systeminformation is to be received in that subframe.

In accordance with another embodiment, a computer program productcomprising a computer-readable medium having a computer-readable programcode embodied thereon is provided, the program code being adapted tocarry out the present disclosure.

Other exemplary embodiments relate to the implementation of the abovedescribed various embodiments using hardware and software. In thisconnection a user terminal (mobile terminal) and an eNodeB (basestation) are provided. The user terminal and base station are adapted toperform the methods described herein, including corresponding entitiesto participate appropriately in the methods, such as receiver,transmitter, processors.

It is further recognized that the various embodiments may be implementedor performed using computing devices (processors). A computing device orprocessor may for example be general purpose processors, digital signalprocessors (DSP), application specific integrated circuits (ASIC), fieldprogrammable gate arrays (FPGA) or other programmable logic devices,etc. They may include a data input and output coupled thereto. Thevarious embodiments may also be performed or embodied by a combinationof these devices.

Further, the various embodiments may also be implemented by means ofsoftware modules, which are executed by a processor or directly inhardware. Also a combination of software modules and a hardwareimplementation may be possible. The software modules may be stored onany kind of computer readable storage media, for example RAM, EPROM,EEPROM, flash memory, registers, hard disks, CD-ROM, DVD, etc.

It should be further noted that the individual features of the differentembodiments may individually or in arbitrary combination be subjectmatter to another embodiment.

It would be appreciated by a person skilled in the art that numerousvariations and/or modifications may be made to the present disclosure asshown in the specific embodiments. The present embodiments are,therefore, to be considered in all respects to be illustrative and notrestrictive.

1. An integrated circuit for controlling a transmitting apparatus, theintegrated circuit comprising: control circuitry which, in operation,generates system information configuration information; and transmittingcircuitry, which is coupled to the control circuitry and which, inoperation, transmits the system information configuration information toa receiving apparatus, the system information configuration informationdefining first subframes, and transmits system information to thereceiving apparatus in the first subframes; wherein, the systeminformation configuration information indicates whether multimediabroadcast scheduling information is used to indicate second subframesfor use in multimedia broadcast communication; when the multimediabroadcast scheduling information is used to indicate the secondsubframes for use in multimedia broadcast communication, the firstsubframes are defined exclusive of the second subframes; and when themultimedia broadcast scheduling information is not used, the firstsubframes are defined according to a subframe scheduling field of thesystem information configuration information, wherein each one of bitsin the subframe scheduling field indicates whether a correspondingsubframe is one of the first subframes.
 2. The integrated circuitaccording to claim 1, wherein a number of the bits in the subframescheduling field is less than or equal to a number of the subframes in aradio frame; none of the bits is associated with a subframe used fortransmission of the system information configuration information, asubframe used for a physical broadcast channel, or a subframe configuredfor the multimedia broadcast communication; and the system informationis transmitted only in subframes indicated by the bits in the subframescheduling field as the first subframes.
 3. The integrated circuitaccording to claim 1, wherein the system information configurationinformation is transmitted either within a master information message ofa radio resource control protocol carried on a physical broadcastchannel or within a system information message of the radio resourcecontrol protocol scheduled in the master information message, and thesystem information configuration information further comprises anindication of frequency resources for the system information includingat least one of: (i) at least one of a location and a number of physicalresource blocks reserved for the system information, and (ii) whetherfrequency hopping is applied.
 4. The integrated circuit according toclaim 1, wherein the receiving apparatus is a machine type communication(MTC) terminal; the system information is MTC system information; andnone of the bits in the subframe scheduling field is associated with asubframe carrying system information for another type of communication.5. The integrated circuit according to claim 1, wherein the systeminformation configuration information includes: a first subframescheduling field and a second subframe scheduling field, each includingsubfields for respective subframes; and scheduling informationindicating to which frames the second subframe scheduling field applies,and the second subframe scheduling field is applied to the framesindicated by the scheduling information whereas the first subframescheduling field is applied to any other frames.
 6. The integratedcircuit according to claim 5, wherein the second subframe schedulingfield has no bits associated with any predefined subframes, and thesystem information configuration information includes a first bitmapapplication bit indicating whether the bits in the first subframescheduling field are applicable to the frames indicated in thescheduling information.
 7. The integrated circuit according to claim 1,wherein the transmitting circuitry, in operation, transmits a masterinformation message on a physical broadcast channel, the masterinformation message including scheduling information concerning firstsystem information which includes the system information configurationinformation, and none of the bits in the subframe scheduling field isassociated with a subframe carrying the first system information.
 8. Theintegrated circuit according to claim 7, wherein the schedulinginformation consists of a predefined number of predefined combinationsof at least two of: first system information size, subframes in whichthe first system information can be scheduled, application of frequencyhopping, frequency hopping pattern, and frequency allocation.
 9. Theintegrated circuit according to claim 1, wherein the bits in thesubframe scheduling field are 10 or 40 bits long.